UC28025Double ended economy high speed PWM controller | DC DC Switching Controllers | 4 | Active | The UC28023 and UC28025 are fixed-frequency PWM controllers optimized for high-frequency switched-mode power-supply applications. The UC28023 is a single output PWM for single-ended topologies while the UC28025 offers dual alternating outputs for double-ended and full bridge topologies.
Targeted for cost-effective solutions with minimal external components. UC2802x devices include an oscillator, a temperature compensated reference, a wide bandwidth error amplifier, a high-speed current-sense comparator, and high-current, active-high, totem-pole outputs to directly drive external MOSFETs.
Protection circuitry includes a current limit comparator with a 1-V threshold, a TTL compatible shutdown port, and a soft-start pin which doubles as a maximum duty-cycle clamp. The logic is fully latched to provide jitter-free operation and prohibit multiple pulses at an output. An undervoltage lockout section with 800 mV of hysteresis assures low start-up current. During undervoltage lockout, the outputs are high impedance. Propagation delays through the comparators and logic circuitry have been minimized while maximizing bandwidth and slew rate of the error amplifier.
Devices are available in the industrial temperature range of –40°C to 105°C. Package offerings are 16-pin SOIC (DW), or 16-pin PDIP (N) packages.
The UC28023 and UC28025 are fixed-frequency PWM controllers optimized for high-frequency switched-mode power-supply applications. The UC28023 is a single output PWM for single-ended topologies while the UC28025 offers dual alternating outputs for double-ended and full bridge topologies.
Targeted for cost-effective solutions with minimal external components. UC2802x devices include an oscillator, a temperature compensated reference, a wide bandwidth error amplifier, a high-speed current-sense comparator, and high-current, active-high, totem-pole outputs to directly drive external MOSFETs.
Protection circuitry includes a current limit comparator with a 1-V threshold, a TTL compatible shutdown port, and a soft-start pin which doubles as a maximum duty-cycle clamp. The logic is fully latched to provide jitter-free operation and prohibit multiple pulses at an output. An undervoltage lockout section with 800 mV of hysteresis assures low start-up current. During undervoltage lockout, the outputs are high impedance. Propagation delays through the comparators and logic circuitry have been minimized while maximizing bandwidth and slew rate of the error amplifier.
Devices are available in the industrial temperature range of –40°C to 105°C. Package offerings are 16-pin SOIC (DW), or 16-pin PDIP (N) packages. |
| Voltage Regulators - Linear, Low Drop Out (LDO) Regulators | 8 | Active | |
UC2823B30V, 2A double ended 1MHz PWM controller with 9.2V/8.4V UVLO and 100% duty cycle, -40C to 85C | AC DC Converters, Offline Switches | 12 | Active | 30V, 2A double ended 1MHz PWM controller with 9.2V/8.4V UVLO and 100% duty cycle, -40C to 85C |
UC282430-V, 1.5A double ended 1MHz PWM controller with 9.2V/8.4V UVLO, 80% duty cycle, -40C to 85C | Voltage Regulators - DC DC Switching Controllers | 4 | Active | The UC1824 family of PWM control devices is optimized for high frequency switched mode power supply applications. Particular care was given to minimizing propagation delays through the comparators and logic circuitry while maximizing bandwidth and slew rate of the error amplifier. This controller is designed for use in either current mode or voltage mode systems with the capability for input voltage feed-forward.
Protection circuitry includes a current limit comparator with a 1-V threshold, a TTL compatible shutdown port, and a soft-start pin which doubles as a maximum duty cycle clamp. The logic is fully latched to provide jitter free operation and prohibit multiple pulses at an output. An under-voltage lockout section with 800 mV of hysteresis assures low start up current. During under-voltage lockout, the outputs are high impedance.
The UC1824 family of PWM control devices is optimized for high frequency switched mode power supply applications. Particular care was given to minimizing propagation delays through the comparators and logic circuitry while maximizing bandwidth and slew rate of the error amplifier. This controller is designed for use in either current mode or voltage mode systems with the capability for input voltage feed-forward.
Protection circuitry includes a current limit comparator with a 1-V threshold, a TTL compatible shutdown port, and a soft-start pin which doubles as a maximum duty cycle clamp. The logic is fully latched to provide jitter free operation and prohibit multiple pulses at an output. An under-voltage lockout section with 800 mV of hysteresis assures low start up current. During under-voltage lockout, the outputs are high impedance. |
UC2825A-EP30V, 2A double ended 1MHz PWM controller with 9.2V/8.4V UVLO and 50% duty cycle, -40C to 85C | AC DC Converters, Offline Switches | 16 | Active | The UC2825A-EP pulse width modulation (PWM) controller is an improved version of the standard UC2825. Performance enhancements have been made to several of the circuit blocks. Error amplifier gain bandwidth product is 12 MHz, while input offset voltage is 2 mV. Current-limit threshold is specified to a tolerance of 5%. Oscillator discharge current is specified at 10 mA for accurate dead-time control. Frequency accuracy is improved to 6%. Startup supply current, typically 100 µA, is ideal for off-line applications. The output drivers are redesigned to actively sink current during undervoltage lockout (UVLO) at no expense to the startup current specification. In addition, each output is capable of 2-A peak currents during transitions.
Functional improvements also have been implemented in this family. The UC2825A-EP shutdown comparator is now a high-speed overcurrent comparator with a threshold of 1.2 V. The overcurrent comparator sets a latch that ensures full discharge of the soft-start capacitor before allowing a restart. While the fault latch is set, the outputs are in the low state. In the event of continuous faults, the soft-start capacitor is fully charged before discharge to ensure that the fault frequency does not exceed the designed soft-start period. The UC2825 CLOCK pin is CLK/LEB in the UC2825A-EP. This pin combines the functions of clock output and leading-edge blanking adjustment and has been buffered for easier interfacing.
The UC2825A-EP has dual alternating outputs and the same pin configuration as UC2825. UVLO thresholds are identical to the original UC2825.
Consult the application report,The UC3823A,B and UC2825A,B Enhanced Generation of PWM Controllers, literature number SLUA125, for detailed technical and applications information.
The UC2825A-EP pulse width modulation (PWM) controller is an improved version of the standard UC2825. Performance enhancements have been made to several of the circuit blocks. Error amplifier gain bandwidth product is 12 MHz, while input offset voltage is 2 mV. Current-limit threshold is specified to a tolerance of 5%. Oscillator discharge current is specified at 10 mA for accurate dead-time control. Frequency accuracy is improved to 6%. Startup supply current, typically 100 µA, is ideal for off-line applications. The output drivers are redesigned to actively sink current during undervoltage lockout (UVLO) at no expense to the startup current specification. In addition, each output is capable of 2-A peak currents during transitions.
Functional improvements also have been implemented in this family. The UC2825A-EP shutdown comparator is now a high-speed overcurrent comparator with a threshold of 1.2 V. The overcurrent comparator sets a latch that ensures full discharge of the soft-start capacitor before allowing a restart. While the fault latch is set, the outputs are in the low state. In the event of continuous faults, the soft-start capacitor is fully charged before discharge to ensure that the fault frequency does not exceed the designed soft-start period. The UC2825 CLOCK pin is CLK/LEB in the UC2825A-EP. This pin combines the functions of clock output and leading-edge blanking adjustment and has been buffered for easier interfacing.
The UC2825A-EP has dual alternating outputs and the same pin configuration as UC2825. UVLO thresholds are identical to the original UC2825.
Consult the application report,The UC3823A,B and UC2825A,B Enhanced Generation of PWM Controllers, literature number SLUA125, for detailed technical and applications information. |
| Integrated Circuits (ICs) | 1 | Obsolete | The UC1825 family of PWM control ICs is optimized for high frequency switched mode power supply applications. Particular care was given to minimizing propagation delays through the comparators and logic circuitry while maximizing bandwidth and slew rate of the error amplifier. This controller is designed for use in either current-mode or voltage mode systems with the capability for input voltage feed-forward.
Protection circuitry includes a current limit comparator with a 1V threshold, a TTL compatible shutdown port, and a soft start pin which will double as a maximum duty cycle clamp. The logic is fully latched to provide jitter free operation and prohibit multiple pulses at an output. An under-voltage lockout section with 800mV of hysteresis assures low start up current. During under-voltage lockout, the outputs are high impedance.
These devices feature totem pole outputs designed to source and sink high peak currents from capacitive loads, such as the gate of a power MOSFET. The on state is designed as a high level.
The UC1825 family of PWM control ICs is optimized for high frequency switched mode power supply applications. Particular care was given to minimizing propagation delays through the comparators and logic circuitry while maximizing bandwidth and slew rate of the error amplifier. This controller is designed for use in either current-mode or voltage mode systems with the capability for input voltage feed-forward.
Protection circuitry includes a current limit comparator with a 1V threshold, a TTL compatible shutdown port, and a soft start pin which will double as a maximum duty cycle clamp. The logic is fully latched to provide jitter free operation and prohibit multiple pulses at an output. An under-voltage lockout section with 800mV of hysteresis assures low start up current. During under-voltage lockout, the outputs are high impedance.
These devices feature totem pole outputs designed to source and sink high peak currents from capacitive loads, such as the gate of a power MOSFET. The on state is designed as a high level. |
UC2827-1Buck current Fed push-pull PWM controller, -40°C to 84°C | Integrated Circuits (ICs) | 4 | Active | The UC3827 family of controller devices provides an integrated control solution for cascaded buck and push-pull converters. These converters are known as current fed or voltage fed push-pull converters and are ideally suited for multiple output and/or high voltage output applications. In both current fed and voltage fed modes, the push-pull switches are driven at 50% nominal duty cycles and at one half the switching frequency of the buck stage. In the current fed mode, the two switches are driven with a specified over-lap period to prevent ringing and voltage stress on the devices. In the voltage fed mode, the two switches are driven with a specified gap time between the switches to prevent shorting the transformer across the energy storage capacitor and to prohibit excessive currents flowing through the devices.
The converter's output voltage is regulated by pulse width modulation of the buck switch. The UC3827 contains complete protection and PWM control functions for the buck converter. Easy control of the floating switch is accomplished by the floating drive circuitry. The gate drive waveform is level shifted to support an input voltage up to 72 VDC.
The UC3827 can be set up in traditional voltage mode control using input voltage feedforward technique or in current mode control. Using current mode control prevents potential core saturation of the push-pull transformer due to mismatches in timing and in component tolerances. With average current mode control, precise control of the inductor current feeding the push-pull stage is possible without the noise sensitivity associated with peak current mode control. The UC3827 average current mode loop can also be connected in parallel with the voltage regulation loop to assist only in fault conditions.
Other valuable features of the UC3827 include bidirectional synchronization capability, user programmable overlap time (UC3827-1), user programmable gap time (UC3827-2), a high bandwidth differential current sense amplifier, and soft start circuitry.
The UC3827 family of controller devices provides an integrated control solution for cascaded buck and push-pull converters. These converters are known as current fed or voltage fed push-pull converters and are ideally suited for multiple output and/or high voltage output applications. In both current fed and voltage fed modes, the push-pull switches are driven at 50% nominal duty cycles and at one half the switching frequency of the buck stage. In the current fed mode, the two switches are driven with a specified over-lap period to prevent ringing and voltage stress on the devices. In the voltage fed mode, the two switches are driven with a specified gap time between the switches to prevent shorting the transformer across the energy storage capacitor and to prohibit excessive currents flowing through the devices.
The converter's output voltage is regulated by pulse width modulation of the buck switch. The UC3827 contains complete protection and PWM control functions for the buck converter. Easy control of the floating switch is accomplished by the floating drive circuitry. The gate drive waveform is level shifted to support an input voltage up to 72 VDC.
The UC3827 can be set up in traditional voltage mode control using input voltage feedforward technique or in current mode control. Using current mode control prevents potential core saturation of the push-pull transformer due to mismatches in timing and in component tolerances. With average current mode control, precise control of the inductor current feeding the push-pull stage is possible without the noise sensitivity associated with peak current mode control. The UC3827 average current mode loop can also be connected in parallel with the voltage regulation loop to assist only in fault conditions.
Other valuable features of the UC3827 include bidirectional synchronization capability, user programmable overlap time (UC3827-1), user programmable gap time (UC3827-2), a high bandwidth differential current sense amplifier, and soft start circuitry. |
| Voltage Regulators - Linear Regulator Controllers | 3 | Active | |
| Voltage Regulators - Linear Regulator Controllers | 4 | Active | |
| Power Management (PMIC) | 8 | Active | |
